The potential role of protein in the absorption of fat

Stabilization of triglyceride emulsions by proteins was studied in vitro using either chemical or optical methods to measure to amount of fat emulsified under standard conditions of emulsification. Concentrations, pH, and degree of digestion of protein emulsifiers were varied to determine how such manipulations affected emulsion stabilization. Proteins from endogenous as well as exogenous sources were capable of stabilizing triglyceride emulsions, and this effect varied with protein concentration. Peptic digests of a prototype protein retained the efficacy of the undigested protein, while further digestion of the protein in pancreatic proteases decreased, but did not abolish, the emulsifying power of the protein. Emulsion stabilization by peptic digests of protein still persisted despite alterations in pH from 1 to 7. Such emulsions were capable of being hydrolyzed by pancreatic lipase and could be absorbed from the gut of bile-deficient rats. These emulsions also speed the initial rates of fat absorption from animals with an intact bile supply. We conclude that stabilization of luminal emulsions by dietary or endogenous protein may facilitate fat absorption similar to the way that detergent-stabilized emulsions have been previously shown to have these effects.

Recombinant human erythropoietin in the treatment of the anemia of prematurity: results of a double-blind, placebo-controlled study

OBJECTIVE

To assess the efficacy of recombinant human erythropoietin (rHuEpo) in the treatment of the anemia of prematurity.

METHODOLOGY

A double-blind, placebo-controlled study was conducted on 80 preterm infants (< or = 32 weeks; postnatal age, 2 to 8 weeks; central hematocrit < or = 35%). Patients were randomly assigned to receive subcutaneous rHuEpo (Eprex, 600 U/kg per week) or an equivalent volume of placebo, for up to 6 weeks. All patients received supplements of vitamin E (25 IU) and iron (3 mg/kg per day). The iron supplement was increased if declining serum ferritin measurements were noted.

RESULTS

Treatment and placebo groups did not differ significantly with respect to mean gestational age, birth weight, hematocrit, or reticulocyte count at study entry. Fewer transfusions were administered to those receiving erythropoietin (7 compared with 21; P = .002). Compared with the placebo group, the infants receiving rHuEpo had a higher mean hematocrit (32.3 +/- 4% vs 29.3 +/- 6.2%; P = .014) and absolute reticulocyte count (223 +/- 73 vs 124.9 +/- 73 x 10(9)/L; P < .001) at the end of the study. The mean neutrophil count was not significantly reduced at study exit (P = .8), nor at any other period during the trial in the rHuEpo group. Intercurrent events (mostly infections) were not increased in the treatment group, although there was one case of sudden infant death syndrome at age 4 months.

CONCLUSIONS

Using a dose of rHuEpo of 600 U/kg per week, this study has shown a clear reduction in the requirement for blood transfusion in preterm infants.

Pancreatic response to intestinal perfusion with lactic acid or acidified albumin

To test the hypothesis that the permeability of weak acids across the intestinal mucosa affects their ability to stimulate pancreatic bicarbonate output, we compared pancreatic bicarbonate secretion in response to intestinal perfusion with an acid presumed to be permeable to cell membranes, lactic acid (90 daltons), and an acid presumed to be impermeable, acidified bovine serum albumin (about 70,000 daltons). These two substances have similar titration curves from pH 2.00 to pH 4.50. In four conscious dogs with pancreatic fistulas, solutions of these weak acids were perfused at 50 ml/15 min into the intestine at concentrations adjusted to deliver 1, 2, or 4 mmol/15 min of acid titratable to pH 4.50 (threshold pH for bicarbonate stimulation) from an initial pH of 2.00 or 3.50. At both pH 2.00 and 3.50 and at all titratable acid loads, bicarbonate secretory responses to lactic acid and acidified albumin were not significantly different. Equal titratable acid loads of HCl produced much larger secretory responses. The data do not support the hypothesis that permeability of weak acids is a factor, but confirm the observation that weak acids are less potent than strong acids in stimulating pancreatic bicarbonate secretion.

Intraluminal calcium binding does not mediate fatty acid-induced pancreatic bicarbonate secretion

Since the chain length dependency of fatty acid-induced pancreatic exocrine secretion parallels that of fatty acid-induced inhibition of gastric emptying, similar mechanisms of action may be involved. An earlier study suggested that binding of calcium might mediate fatty acid-induced inhibition of gastric emptying. This study investigated possible mediation of fatty acid-induced pancreatic secretion by calcium binding. Pancreatic secretory response to intraduodenal administration of dodecanoate and various calcium chelators (sodium EDTA, calcium-saturated EDTA, sodium dodecyl sulfate, sodium dioctyl sulfosuccinate, and sodium taurocholate) was studied in three dogs equipped with chronic pancreatic fistulae. Calcium affinity of the various test solutions was quantitated by titrating aliquots of perfusate against a standard CaCl2 solution. Sodium EDTA was found to be the most potent calcium binder (pKc 8.3); sodium dodecanoate, sodium dodecyl sulfate, and sodium dioctyl sulfosuccinate were moderate calcium binders (pKc 7.3, 7.2, 6.9, respectively), whereas sodium taurocholate and calcium-saturated EDTA were poor calcium binders. Sodium dodecanoate evoked brisk bicarbonate output (0.6-1.6 mEq/15 min). Minimal secretory responses were observed in response to all other agents tested. These findings suggest that calcium binding is not involved in mediation of fatty acid-induced pancreatic bicarbonate secretion.

Gastric emptying of liquid meals and pancreatic and biliary secretion after subtotal gastrectomy or truncal vagotomy and pyloroplasty in man

Pancreatic and biliary secretion and gastric emptying rates of a liquid test meal (LTM) were determined in normal persons, in patients with subtotal gastrectomy with gastroduodenostomy (STG-BI) or with gastrojejunostomy (STG-BII), and in patients with truncal vagotomy and pyloroplasty (V&P). In all operated persons, rapid gastric emptying diluted intraluminal contents, with consequent abnormally low concentrations of trypsin and bile salts initially, a pattern that was not corrected by addition of intravenous hormones to the meal stimulus. Trypsin output in V&P's after the LTM was significantly depressed to 40% of normal, but was normal in the STG groups. The delay in reaching normal values for trypsin and bile salt concentrations, was more marked in STG-BII owing to sequestration of secretions in the afferent loop. The low luminal concentrations of digestive secretions for the first 60 to 80 min after a LTM are therefore attributable to rapid gastric emptying in all operated groups, and in V&P to a depressed pancreatic enzyme response also. In STG-BII, afferent loop sequestration exaggerates the delay in attainment of normal intraluminal concentrations. The combined disturbance in STG-BII produces greater abnormalities than seen in STG-BI.

The effect of acute hyperglycemia on meal-stimulated gastric, biliary, and pancreatic secretion, and serum gastrin

The effects of hyperglycemia on pancreatic, biliary, and gastric secretory responses to meals have not been hitherto quantified in man. In the present study seven normal volunteers were fed on two occasions a 500-ml liquid test meal containing fat and protein. During one of the meals the subjects were made acutely hyperglycemic with intravenous glucose, whereas in control experiments, each subject received intravenous saline in place of glucose. A jejunal perfusion method was used to measure pancreatic outputs of trypsin and biliary outputs of bile salts for 150 min after the meal; the same method was used to quantify indirectly the amount of acid secreted by the stomach in the 150-min period. Serum gastrins were also measured basally and at intervals after the meal. Hyperglycemia suppressed serum gastrin, gastric acid production, trypsin secretion, and bile salt output in response to the test meal.

SupraPetrous InfraTemporal Approach: A Supplemental Approach to Supracerebellar Infratentorial for Inferior Amygdala and Hippocampal Head Access-A Cadaveric Study With Case Illustrations

BACKGROUND AND OBJECTIVES

Access to the amygdala and hippocampus (A/H) is complex. To address the limitations and invasiveness of traditional approaches, including the Transsylvian, Subtemporal, and Supracerebellar infratentorial approaches, we developed the suprapetrous infratemporal (SPIT) approach. This study describes the nuances of this approach in both cadaveric studies and clinical cases.

METHODS

Three unilateral exposures were performed using microscopic and endoscopic methodologies in the SPIT approach. After cadaveric investigation, this approach was successfully implemented in representative clinical cases.

RESULTS

The SPIT approach enabled direct access to the inferior A/H, circumventing the requirement for temporal lobe retraction and detachment of the temporal lobe from the dura through a subtemporal route by drilling the upper part of the mastoid, consequently mitigating tension on the vein of Labbé. This enabled a bottom-up view because one would gain with a zygomatic osteotomy and forward projection like a mini-posterior petrosal view by using a transmastoid view, without cutting down the zygomatic arch and opening the dura subtemporally, limiting patient pain and preventing case comorbidity. The SPIT approach was performed in 2 cases of mesial temporal cavernoma presenting with seizures. The lesion was visualized intraoperatively and was successfully removed in these cases. The postoperative course was excellent with no complications, and gross total resection was radiographically confirmed with Engel Class 1a seizure freedom.

CONCLUSION

The SPIT approach is a complementary approach for inferior A/H disease, combining the combined middle fossa approach modified for intradural pathology. Limited drilling of the upper aspect of the mastoid with a medial dural opening at the level of the arcuate eminence provides a direct trajectory with minimal brain retraction. Additional research encompassing a larger patient cohort and extended follow-up periods is required to substantiate the advantages of SPIT in the management of inferior A/H lesions.

[Variability of findings in light sense and ring perimetry]

The variability of the interpretation of visual fields by physicians has so far been thoroughly examined only with reference to light sense perimetry. Therefore, we studied the variability in assigning visual fields to topical diagnoses of the visual pathway with the ring perimeter. For this purpose we examined the proportion of correct assignments of physicians and the reproducibility of their assignments. Two experienced ophthalmologists had to assign 76 selected pairs of right and left visual fields to one of the following diagnosis without any information about further clinical findings: (1) normal (n = 5), (2) media opacity (n = 5), (3) retinal lesion (n = 5), (4) optic disc lesion (n = 6), (5) optic nerve lesion (n = 6), (6) lesion of the chiasma (n = 5) and (7) retrochiasmal lesion (n = 6). The assignment was repeated after intervals of 6 weeks and 10 months. Our statistical analysis of the number of correct assignments revealed no significant differences between the perimeters or between the physicians. The amount of correct assignments with both perimeters decreased from 75% and 66% during the first run through 60% and 70% during the second run to 58% and 60% during the third. Neither perimeter showed any major differences in the reproducibility of the assignments (Fig. 4). During the three runs only 47% (physician 1) and 58% (physician 2) of the cases were assigned three times to the same diagnoses with the octopus. The corresponding figures for the ring perimeter were 58% and 60%. This is regarded as an indicator of the unreliability in the interpretation of visual fields.

Effects of Furegrelate (Upjohn 63557A) on patency and platelet deposition after canine carotid endarterectomy

Platelet deposition upon endarterectomy sites is a likely cause for early postoperative thrombosis, embolism and restenosis. Platelets aggregate by the thromboxane-prostacycline mechanism. Thromboxane synthetase inhibitors which have been safely administered to humans should reduce platelet deposition after surgical therapy and therefore reduce peri-operative mortality and the prevalence of stroke. A randomized prospective controlled trial was designed to determine vessel patency and platelet deposition associated with the use of 3 mg/kg and 30 mg/kg of Furegrelate (Upjohn U63557A) daily in dogs, who were to have carotid endarterectomy. The 46 treated and 46 control dogs had total carotid patency of 96% and 76% respectively (P less than 0.01). Fourteen dogs treated with 30 mg/kg Furegrelate had no occlusions, compared with a 19% prevalence in 13 controls (P less than 0.02). Furegrelate 10 mg/kg significantly lowered platelet aggregation. Platelet deposition was not significantly changed, however. The reason for this disparity was a probable persistence of vessel wall factors which promoted platelet deposition. This approach might therefore lower rates of peri-operative thrombosis but it would be very unlikely to alter the incidence of restenosis or embolism. Further research could be directed towards modifying the stimuli for platelet deposition upon the endarterectomy site.

Gastric emptying of solid food in normal man and after subtotal gastrectomy and truncal vagotomy with pyloroplasty

Alterations in gastric emptying are considered contributory to many sequelae of peptic ulcer surgery. The application of a validated method of firmly tagging solid food has enabled the measurement of the rates and patterns of gastric emptying in normal subjects, subtotal gastrectomy, and vagotomy and pyloroplasty (V&P). Normal persons emptied with a linear pattern at a mean rate of 27.96% per hr. Subtotal gastrectomy patients showed up to three phases in their emptying pattern, which, over all, approximated an exponential pattern with a mean rate constant of 0.030 min-1 and calculated t1/2 of 23.3 min. V&P subjects divided into two groups: (1) slow emptying with a linear pattern and mean rate of 17.64% per hr; (2) rapid emptying with exponential pattern and mean rate constant of 0.039 min-1, t1/2 of 17.7 min. The slow gastric emptying rate and slow passage of chyme through the small intestine in one-half of the V&P group presumably allows greater efficiency of digestion and absorption and may account for the over-all less severe nutritional disturbances after V&P.

Cimetidine versus intensive antacid therapy for duodenal ulcer: a multicenter trial

In a randomized double blind multicenter trial, patients treated with cimetidine (800 or 1200 mg daily) or an intensive regimen of Al-Mg antacid (210 ml daily) had similar rates of duodenal ulcer healing and pain relief. After 4 weeks of treatment, the proportion of patients with ulcer healing by endoscopy were: cimetidine (1200 mg), 21 of 33 (64 percent); cimetidine (800 mg), 19 of 32 (59 percent); and antacids, 15 of 29 (52 percent). These proportions did not differ significantly. Eighty per cent of cimetidine-treated patients became asymptomatic by week 4, as did 63 percent of antacid-treated patients (P greater than 0.1). No untoward effects were observed during cimetidine treatment. Twenty-seven per cent of antacid-treated patients reported diarrhea.

Further clinical experiences of a phase I study with the hypoxic cell radiosensitizer misonidazole

Since April 1976 we have performed clinical investigations with multiple doses of the hypoxic cell radiosensitizer misonidazole in 21 patients. A significant side effect of the drug was the development of peripheral sensory neuropathies in 13 patients (8 mild, 5 severe) and of a transient acute organic psychosyndrome in 2 of the 5 patients with a severe polyneuropathy. The severity of the polyneuropathies is related to the total dose of misonidazole and the overall time of drug administration. Treatment schedules designed to obtain the desired sensitizing effect without neurological side effects are under investigation.

Gastric emptying rates of solid food in relation to body size

The relationship of body size to rates of gastric emptying of solid food was investigated in order to obtain data that may allow this variable to be considered when populations of varying size are studied. Rates of gastric emptying were measured using a beef stew meal to which were added pieces of chicken liver tagged with [99mTc]sulfur colloid, and following the passage of the isotope through the gastrointestinal tract with intermittent gamma-imaging. Results showed an inverse linear relationship between gastric emptying rates and body surface area, and between gastric emptying rates and body weight. The variable of body size must be taken into account when measurements of gastric emptying of solid food are measured.

Effect of hydroxypropylmethylcellulose on gastrointestinal transit and luminal viscosity in dogs

The effects of hydroxypropylmethylcellulose on upper gastrointestinal transit, viscosity, and water flux were studied in six dogs fistulated at the proximal duodenum and/or mid-jejunum. Combinations of different grades of hydroxypropylmethylcellulose were prepared as 2% or 3.3% solutions to yield input viscosities of low (approximately 5000 cp at 37 degrees C and 1 s-1), medium (15,000 cp), or high (30,000 cp) viscosity. Hydroxypropylmethylcellulose modified intralumenal viscosity, with a linear relationship existing between input and lumenal viscosity. With regard to transit, the lag time before the onset of chyme recovery increased linearly as a function of luminal viscosity. There was also a pronounced decrease in the first-order emptying rate constant as lumenal viscosity increased from water to low-viscosity hydroxypropylmethylcellulose, but as viscosity was further increased there was little additional change. These results indicate that water-soluble fibers can exert a significant influence on both the lumenal viscosity and the transit profile in the upper gastrointestinal tract.

Release of secretin along the canine small intestine

The profile of secretin release along the entire canine small intestine was examined in this study. Four equal loops of the small gut, from the duodenal bulb to the ileocoecal valve, were isolated. In eight anesthetized dogs the four segments were perfused for 40 min each in random order with an acidified (pH 2.5) emulsion of 20 mM oleic acid. In four dogs control experiments were performed using 0.15 M saline. Secretin release in portal venous blood was measured by a sensitive radioimmunoassay. Although secretin was mainly released in the first quarter of the small intestine (310 pM X 40 min), large amounts of secretin, 33% of the total secretin release, were liberated in the second quarter of the small intestine (164 pM X 40 min). Minute amounts of secretin (23 pM X 40 min) were released in the third quarter, whereas perfusion of the last quarter of the small gut failed to release secretin. We conclude that the major portion of secretin is releasable in the first quarter of the small gut. High amounts of secretin can be liberated in the second quarter of intestine, an area that is probably never exposed to pH below 4.5 (the known threshold for secretin release by acid), but is still exposed to fatty acids (other releasers of secretin).

Effect of peptic digestion on emptying of cooked liver in dogs

By speeding the fragmentation of meat, peptic digestion might accelerate gastric emptying. To examine this possibility, mongrel dogs prepared with chronic duodenal fistulas were fed steak and 99mTc-labeled chicken liver, measuring 99mTc in all chyme exiting from the stomach out the duodenal fistula allowed quantitation of the gastric emptying of 99mTc-liver. Emptying was studied during relatively uninhibited gastric propulsion when the proximal bowel was perfused with chyme or fat. When chyme was diverted, the speed of emptying varied with peptic activity in the stomach--that is, it was increased by orogastric perfusion with acid-pepsin (vs. a control perfusion of pH 7 buffer) or, alternately, was decreased from the unperfusion stomach by i.v. cimetidine (vs. i.v. saline). By contrast, no effect of altering peptic conditions was observed when chyme was allowed access to the proximal bowel (the more normal situation), or when the duodenum was perfused with fat. We conclude that duodenal inhibition may override the effect of peptic digestion on the emptying of liver. We postulate that inhibition of gastric contractions limits the grinding of liver into particles susceptible to peptic digestion.